Single-beam holography using anisotropic self-diffraction

Abstract

We report a new kind of single incident beam holography. In this method, we use only one beam instead of two beams to make gratings inside photorefractive cerium doped barium titanate. The configuration of the method is based on an anisotropic self-diffraction scheme. The reflection of self-phase conjugate beam at the surface of incidence plays the role of the second beam. By using the reflection of the self-phase conjugate beam, the difficulty of alignment between two focused writing beams has been eliminated. The autocorrelation images in non-Bragg orders have been monitored in order to verify the effectiveness of this method for writing holograms. INTRODUCTIONImage correlation using higher non-Bragg order self-diffraction in photorefractive (PR) materials has been investigated by our group for more than a decade [1,2,3]. Anisotropic self-diffraction (ASD) has been of interest to researchers for sometime. In this set up, the writing beams need to be at some specific angles with each other in order to generate the higher orders with polarization perpendicular to the incident beams. The writing beams are simultaneously diffracted by their own gratings and thus generate higher orders. Recently, higher order beams from the anisotropic self-diffraction scheme have been used for image correlation [4,5].Recording a hologram by using one incident beam is interesting because it may give us more choices to write a hologram using cheaper semiconductor lasers which have short coherent length, and simplifies the need for exact alignment of the incident signal and reference beams in the crystal. To the best of our knowledge, three single incident beam holography configurations have been developed. The first configuration developed by Kukhtarev et. al. [6] uses the interaction of two orthogonally polarized eigenmodes split from one incident beam via photogalvanic effect in a birefringent photogalvanic crystal. The second one developed by Naruse et. al. [7] uses the interaction between two beams which is split from one input incident beam at the corner of the crystal. The last one developed recently by Liu et. al. [8] uses the interaction between the fanning light from one input beam incident on LiNbO 3 . Recently, we have demonstrated single beam ASD [9]. In this configuration, the self phase conjugate (PC) beam reflected from the inicdent surface is used as another writing beam. Although the power ratio between the incident and reflected phase conjugate beam (RPC) is low, higher orders still have been observed. In this paper, autocorrelation images of one incident beam ASD have been shown to prove the validity of recording a hologram by using single beam. ANISOTROPIC SELF-DIFFRACTIONSince ASD in PR media was first introduced by Kukhtarev et. al.[10], the effect has been investigated intensively in recent years. Recently Wang et. al. developed the theory of phase mismatched ASD [11]. One of the interesting properties of ASD is that the polarization of the higher order beams is perpendicular to the polarization of the inci...